This usually signifies a bit of an active pattern, which explains why we can expect rain chances in the future. The jet stream, as depicted by the arrows, is pushing the storm from the west to the east.
As the pattern progresses, the jet stream pushes that feature from the west to the east. Now and then, we can get storms here to move in from the east, but it takes a big perturbation in the jet stream to do so.
In June 1989, Pacific Hurricane Come traveled across North America and became Atlantic Tropical Storm Allison. In July 1985, Hurricane Bob crossed Florida from west to east, tracked north along the Florida coast, made landfall on the southern coast of South Carolina as a tropical storm, and finally traveled north through Western Virginia.
However, if you live closer to the equator, toward the tropics, the weather patterns tend to move west and come out of the east. If you live in the United States, you can usually expect winds and weather patterns out of the west.
However, if you live closer to the equator, you can expect winds and weather patterns to come of the East. Weather generally in Southern Hemisphere moves from the west to the east.
These maps show winter temperature patterns (top) and winter precipitation patterns (bottom) associated with a curvy jet stream (not shown) that moves north from the Pacific to the Yukon and Alaska, then plunges down over the Canadian plains and into the eastern United States. The curvy jet stream brought abnormally warm temperatures (red and orange) to the West and Alaska and an abnormal deep freeze (blue) to the East this past winter, similar to what is shown in the top map, except the upper Midwest was colder than shown.
Last winter's curvy jet stream pattern brought mild temperatures to western North America and harsh cold to the East. A University of Utah-led study shows that pattern became more pronounced 4,000 years ago, and suggests it may worsen as Earth's climate warms.
“If this trend continues, it could contribute to more extreme winter weather events in North America, as experienced this year with warm conditions in California and Alaska and intrusion of cold Arctic air across the eastern USA,” says biochemist Gabe Bowen, senior author of the study. “A sinuous or curvy winter jet stream means unusual warmth in the West, drought conditions in part of the West, and abnormally cold winters in the East and Southeast,” adds Bowen, an associate professor of geology and geophysics at the University of Utah.
It is not new for scientists to forecast that the current warming of Earth's climate due to carbon dioxide, methane and other “greenhouse” gases already has led to increased weather extremes and will continue to do so. Bowen and his co-authors analyzed previously published data on oxygen isotope ratios in lake sediment cores and cave deposits from sites in the eastern and western United States and Canada.
They reveal jet stream directions during the past 8,000 years, a geological time known as middle and late stages of the Holocene Epoch. The Pacific North American reconnection, or PNA, “is a pattern of climate variability” with positive and negative phases, Bowen says.
As it comes in from Hawaii and the Pacific, it tends to rocket up past British Columbia to the Yukon and Alaska, and then it plunges down over the Canadian plains and into the eastern United States. In years when the jet stream pattern is more flat than curvy, “we tend to have strong storms in Northern California and Oregon.
The ratio of rare, heavy oxygen-18 to the common isotope oxygen-16 in the calcium carbonate tells geochemistry whether clouds that carried the rain were moving generally north or south during a given time. Then the jet stream curves south over the middle of the continent, and the water vapor, already depleted in oxygen-18, falls in the East as rain with lower oxygen-18-to-16 ratios.
By examining oxygen isotope ratios in lake and cave sediments in the West and East, Bowen and colleagues showed that a flatter jet stream pattern prevailed from about 8,000 to 4,000 years ago in North America, but then, over only 500 years, the pattern shifted so that curvy jet streams became more frequent or severe or both. Some sites provided oxygen isotope data; others showed changes in weather patterns based on tree ring growth or spring deposits.
As a test of what the cave and lake sediments revealed, Bowen's team did computer simulations of climate using software that takes isotopes into account. He envisions a tipping point 4,000 years ago when weakening summer sunlight reduced the equator-to-pole temperature difference and, along with an intensifying El Niño climate pattern, pushed the jet stream toward greater curliness.
Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The term “polar vortex” dates back to at least 1853, but names for the phenomenon shifted when scientists began to study it in earnest in the 20th century.
The polar vortices found in the troposphere are generally much larger than the ones in the stratosphere and usually affect weather down on the ground, chilling our bones here on the planet's surface. These big, swirling air masses normally hover over the North and South poles in the wintertime.
Without a strong low-pressure system in place to maintain typical weather patterns, the jet stream starts to move around the earth. If that jet stream should encounter a high-pressure system, full of dry light winds, that can act as a choke point for the vortex.
The system can break off and float southbound, right down to the U.S. States as far south as Florida can experience conditions typically reserved for higher, chillier latitudes. A tremendous high-pressure system over Greenland allowed for the jet stream to move south with a vortex in tow.
Anybody who experienced the brutal weather, felt especially in the Chicago land metropolitan area, had to live through temperatures in the negative teens Fahrenheit, the lowest in 20 years. In rural North Dakota, temperatures hit -22 degrees Fahrenheit with a -50-degree wind chill.
Farmers scramble to prepare and care for their crops; vineyards, for example, are at risk of losing their coveted grapes. One group of climate scientists found “robust relationships” between Arctic warming and jet-stream wavering.
In 2015, they predicted that “the frequency of extreme weather events caused by persistent jet-stream patterns will increase.” Some, however, are less concerned about the intensity of jets of cold weather dipping into the subtropics because the average temperatures in the Arctic are increasing so rapidly.
This content is created and maintained by a third party, and imported onto this page to help users provide their email addresses. A person might be interested in knowing about their local wind patterns for planning windbreaks, directing air flow, avoiding unwanted odor or air pollution plumes, designing an airport, or many other reasons.
In the mid-latitudes of North America, Europe and Asia, winds move west to east, naming them the Westerlies. Here, in the United States, it is common for weather patterns to follow winds in a west to east movement.
This monsoon occurs as moist air over the Pacific Ocean and Gulf of Mexico travels north and west to the dry areas of the Western United States, bringing the rain to the deserts and causing a change in the persistent winds for a time. Things nearby that may influence your wind patterns are mountains, oceans and other large bodies of water, forest boundaries, urban areas and other variations in elevation, moisture or temperature.
Some weather stations provide easily accessible long-term data where prevailing wind directions may be found by month or year. Here is a link provided by the United States Natural Resource Conservation Service (http://www.wcc.nrcs.usda.gov/ftpref/downloads/climate/windrose/) with prevailing winds by location and month.
The strength and direction of prevailing winds are helpful to understand and plan for when deciding tree species and planting locations. Properly chosen tree species will withstand any prevailing wind issues in your location.
The summer high pressure ridge, sometimes referred to as a “heat dome,” has set air pressure records as recorded by weather balloons in Pittsburgh and Virginia, and has been responsible for sending air temperatures rocketing into the mid- to upper-90s, and even the lower triple digits, in some parts of the East. The heat index, which is a measure how the temperature feels to the humid body, has reached the dangerous range of 105 to 115 °F in some spots.
In New York’s Central Park, the overnight low on Wednesday night into Thursday morning was 79 °F, tying a record for the highest such temperature for the date. The National Weather Service issued heat warnings and advisories for nearly two-dozen states on Thursday, with a smaller number to be affected on Friday in the densely populated Mid-Atlantic and Northeast.
In addition to the Bermuda leaving its more tropical locale and camping out in Michigan, an area of low pressure at the upper levels of the atmosphere has also been roaming the U.S. since July 11, drifting from east to west, traveling from the Mid-Atlantic states to Texas, where it brought some welcome rainfall. With the jet stream (in blue and green) located far to the north, over Canada, weather systems have drifted from east to west across the U.S. Credit: Weatherbell.com.
In recent years there have been numerous instances of strong and long-duration high pressure areas that have led to extreme weather events, including the Russian heat wave of 2010. “It would take considerable time to crunch through the data and utilize a methodology to accurately pick events like this that have occurred in the historical record and quantify .